/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.ComponentModel;
using System.Drawing;
using System.Globalization;
using Spring.Util;

namespace Spring.Core.TypeConversion;

/// <summary>
/// Converter for <see cref="System.Drawing.Color"/> from a comma separated
/// list of RBG values.
/// </summary>
/// <remarks>
/// <p>
/// Please note that this class does <b>not</b> implement converting
/// to a comma separated list of RBG values from a
/// <see cref="System.Drawing.Color"/>.
/// </p>
/// </remarks>
/// <author>Federico Spinazzi</author>
public sealed class RGBColorConverter : TypeConverter
{
    private const char ArgbSeparator = ',';

    private const string DefaultAlpha = "255";

    /// <summary>
    /// Returns whether this converter can convert an object of one
    /// <see cref="System.Type"/> to a
    /// <see cref="System.Drawing.Color"/>.
    /// </summary>
    /// <remarks>
    /// <p>
    /// Currently only supports conversion from a
    /// <see cref="System.String"/> instance.
    /// </p>
    /// </remarks>
    /// <param name="context">
    /// A <see cref="System.ComponentModel.ITypeDescriptorContext"/>
    /// that provides a format context.
    /// </param>
    /// <param name="sourceType">
    /// A <see cref="System.Type"/> that represents the
    /// <see cref="System.Type"/> you want to convert from.
    /// </param>
    /// <returns><see langword="true"/> if the conversion is possible.</returns>
    public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
    {
        if (sourceType == typeof(string))
        {
            return true;
        }

        return base.CanConvertFrom(context, sourceType);
    }

    /// <summary>
    /// Converts the specified object (a string) a <see cref="System.Drawing.Color"/>
    /// instance.
    /// </summary>
    /// <param name="context">
    /// A <see cref="System.ComponentModel.ITypeDescriptorContext"/>
    /// that provides a format context.
    /// </param>
    /// <param name="culture">
    /// The <see cref="System.Globalization.CultureInfo"/> to use
    /// as the current culture: currently ignored.
    /// </param>
    /// <param name="value">
    /// The value that is to be converted, in "R,G,B", "A,R,G,B", or
    /// symbolic color name (System.Drawing.KnownColor if on .NET Full Framework).
    /// </param>
    /// <returns>
    /// A <see cref="System.Drawing.Color"/> representation of the string value.
    /// </returns>
    /// <exception cref="System.FormatException">
    /// If the input string is not in a supported format, or is not one of the
    /// predefined system colors (System.Drawing.KnownColor if on .NET Full Framework).
    /// </exception>
    public override object ConvertFrom(
        ITypeDescriptorContext context, CultureInfo culture, object value)
    {
        string input = value as string;
        if (StringUtils.HasText(input))
        {
            if (input.IndexOf(ArgbSeparator) > -1)
            {
                string[] colorSplit = input.Split(ArgbSeparator);
                if (colorSplit.Length == 3)
                {
                    return FromRgb(colorSplit);
                }
                else if (colorSplit.Length == 4)
                {
                    return FromArgb(colorSplit);
                }
                else
                {
                    throw new FormatException(
                        "Input string is not in the correct format : '" + input + "'.");
                }
            }

            return FromName(input);
        }

        return base.ConvertFrom(context, culture, value);
    }

    private static object FromRgb(string[] rgb)
    {
        return GetColorFrom(DefaultAlpha, rgb[0], rgb[1], rgb[2]);
    }

    private static object FromArgb(string[] argb)
    {
        return GetColorFrom(argb[0], argb[1], argb[2], argb[3]);
    }

    private static Color FromName(string name)
    {
#if NETSTANDARD
        throw new NotSupportedException("FromName is not supported under .NET Core");
#else
            try
            {
                KnownColor color = (KnownColor) Enum.Parse(typeof(KnownColor), name);
                return Color.FromKnownColor(color);
            }
            catch (Exception ex)
            {
                throw new FormatException(
                    "Input string is not a known system color : '" + name + "'.", ex);
            }
#endif
    }

    private static Color GetColorFrom(string alpha, string red, string green, string blue)
    {
        try
        {
            return Color.FromArgb(Int32.Parse(alpha), Int32.Parse(red), Int32.Parse(green), Int32.Parse(blue));
        }
        catch (Exception ex)
        {
            throw new FormatException(
                "Bad color format.", ex);
        }
    }
}
